This invention relates to a transfer needle for loop-forming machines making flat textile knitwear.
For making, for example, patterned knitwear, circular knitting machines with cylinder needles and dial needles may be used. Dependent on the pattern, individual loops are transferred from the cylinder needles to the dial needles and conversely. For this purpose special needles are used which have loop transfer elements and are designated as transfer needles.
German Patent No. 42 31 015 discloses transfer needles configured as compound needles which have a slide extending longitudinally along the needle shank and serve for opening and closing a hook (head) carried by the needle shank. A transfer spring secured to the side of the compound needle defines with the needle shank an intermediate space through which the hook and the shank of another needle may pass. The transfer spring is held only at one of its ends on the needle shank. For a suitable configuration of the intermediate space between the transfer spring and the needle shank the latter is provided with a recess which intersects the slide as well as the shank.
The intersecting faces of the slide and the shank each form guide faces which are to facilitate the penetration of another needle into the intermediate space.
German Patent No. 1,560,996 discloses a transfer needle which is configured as a latch needle rather than a compound needle. Accordingly, it has a solid needle shank without a slide element. To effect loop transfer, the latch needle has a laterally bent shank. That part of the shank which extends from the hook and which is designated as the main shank is of stepped structure having a high and a low portion. Starting from the low portion, a groove extends over the needle back to the high shank portion in which the groove is entirely open towards the side face of the needle.
A lateral bent portion of the shank is, however, in many instances undesirable.
German Patent No. 31 45 708 discloses a transfer needle for flat knitting machines. The needle has a transfer spring on its side for transferring the loops. The spring is a leaf spring and is affixed at one of its ends to the needle shank. The other, free end of the leaf spring forms, together with the needle shank, an intermediate space into which another needle may penetrate with its hook and shank. The leaf spring as well as the needle shank are, at their respective underside, provided with an oblique guide face which is intended to facilitate the penetration of another needle into the intermediate space between the transfer spring and the needle shank. The guide face provided on the shank is substantially planar and extends from the needle back to the outer side face of the needle.
Particularly the transfer spring of the transfer needle is exposed to substantial dynamic loads during operation. For the loop transfer first the hook and one part of the shank of another transfer needle enters the intermediate space in the vicinity of the free end of the transfer spring. This event may already cause the free end of the transfer spring to be pushed away laterally from the needle shank at which the transfer spring is secured. If such an occurrence takes place in a narrow needle guide channel where the transfer spring lies against the channel flanks, the transfer spring may undergo substantial local bending deformations which lead to high stresses. If such an occurrence causes breakage of the spring, the transfer needle becomes useless, and the knitting machine has to be stopped for servicing.